Although combination antiretroviral therapy (CART) has been highly successful in reducing mother-to-child- transmission (MTCT) in the U.S., globally, MTCT is presently responsible for >1000 new HIV-1 infections each day or more than one new pediatric infection every two minutes. The dopamine (DA) system is a clinically relevant target as evidenced by recent imaging, neurocognitive, and post-mortem examinations of the HIV-1 infected patients. Using a prospective longitudinal design, in this competing renewal we will explore the hypothesis that the development and progression of neurocognitive dysfunction associated with HIV-1, is consequent of, and attributable to, pathology of the DA system, a system highly sensitive to inflammatory processes. Longitudinal studies, while challenging in non-rodent species, are critical for systematically addressing pediatric HIV-1/AIDS, and are also fundamental to our understanding of chronic HIV-1 associated neurological disorders (HAND). The specific aims are: 1) To determine the development and progression of neurocognitive dysfunction consequent to chronic, low-level inflammation and HIV-1 protein exposure. Developmental milestones and an array of tasks directed at the behaviors expressing the prominent components of neurocognitive dysfunction that have been clinically identified will be assessed during the rodent preweaning period, adolescence, adulthood and middle age. 2) To determine the long-term alterations in the major DA receptor subtypes and DA transporter as a candidate neurochemical mechanism for the neurocognitive dysfunction consequent to chronic, low-level inflammation and HIV- 1 protein exposure. Quantitative autoradiography will be used to assess the expression of DA receptors (D1, D2, and D3) and DA transporters (DAT) in the nigrostriatal and mesocorticolimbic pathways of the DA system during adolescence, adulthood and middle age. 3) To determine the integrity of DAT function in the development and progression of neurocognitive dysfunction consequent to chronic, low-level inflammation and HIV-1 protein exposure. DAT function will be studied in a transgenic rat model of chronic HIV-1 protein exposure using in vivo NNF/microdialysis. 4) To determine whether the neurocognitive dysfunction consequent to chronic, low-level inflammation and HIV-1 protein exposure may be treated with currently used agonists or antagonists, or novel agents, targeted to the identified DA system dysfunction. These experiments will establish the functional role of the neurobiological changes in the DA receptors and DAT as a neurochemical mechanism contributing to, if not mediating, the neurocognitive impairments consequent to chronic expression of the HIV-1 transgene. The program goal is to advance the field with a translational model of the core components of cognition relevant to pediatric HIV-1/AIDS as well as to HAND, and more importantly, to identify (normal rats) and validate (the better characterized HIV-1 transgenic rat) novel neurotherapeutics to tune the cognition domains afflicted by HIV-1.